This invention relates to brake boosters for use in a braking system, and more particularly to an airvalve assembly for a brake booster.
The use of a brake booster in a braking system is well known. The brake booster typically comprises front and rear housing parts which are joined around their outer peripheral edge, a flexible diaphragm secured inside the housing to define front and rear chambers within the housing, and an input member which allows relatively high pressure fluid to enter one of the chambers and boost the output braking force.
In general, such designs provide a constant boost ratio throughout their operating range. However, systems have also been proposed to obtain more than one ratio. U.S. Pat. No. 5,699,713, for example, shows a brake booster having a spring arranged to yield under a predetermined force to change the ratio of operative surface areas and thereby increase the boost ratio. U.S. Pat. No. 5,884,548 teaches a brake booster in which an adjusting mechanism is compressible so as to develop a greater degree of pressure differential when a force applied by an input rod exceeds a predetermined level. U.S. Pat. No. 5,893,316 discloses a brake booster that includes a spring that is compressed when a brake reaction exceeds a preset load, and a servo ratio can be established by the choice of areas of contact between a reaction disc and other components.
Often a large spring is required in these designs to achieve proper performance. When space is at a premium, such large springs are a disadvantage.
The present invention is an airvalve assembly for a brake booster of a motor vehicle. The airvalve assembly comprises first and second members movable relative to each other to allow the passage of fluid, and a clip. The clip engages one of the first or second members, and has a spring arm which engages the other of the first or second members to normally position the first and second members relative to each other.
An object of the present invention is to provide an airvalve assembly of the type described above which is relatively compact for the performance achieved.
Another object of the present invention is to provide an airvalve assembly of the type described above in which the clip performs the functions of locating at least a portion of the airvalve assembly and providing a preloaded spring force.
The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiment, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.